Identification of electromagnetic transmitters has long been a technical issue for various government and commercial entities. Sometimes locating the emitter assists in the identification process, but when an adversarial emitter is intermingled with friendly emitters, then additional identification techniques may be needed to determine whether the emitter is friend or foe, or whether it is legitimate or not. Specific Emitter Identification (SEI) and Signal-Of-Interest (SOI) determination is significant for both the defense and commercial industries in support of wireless spectrum management, cognitive radio networks, and the general security of wireless networks.
Many different types of signal processing methods have been employed for SEI. One method utilizes specific signal parameter estimation to allow for feature extraction that may identify the emitter. A different method utilizes statistical and cyclo-stationary parameter pattern recognition up through second-order statistics to distinguish different emitters from one another. Another method uses confusion matrices that may or may not be combined with feature extraction to identify the emitter's type of modulation as another parameter for a feature vector that may help distinguish one emitter from others. An alternative method employs capturing the emitter's various identification codes (typically temporary) such as its international mobile subscriber identity (IMSI). An additional method utilizes spectral analysis and waterfall displays. Still another method uses Radio Frequency (RF) fingerprinting. Some systems for the detection of malware in a computing device may employ signature-based detection. Such systems may also monitor the behavior or activity of applications on a computing device.